It is common for owners of vehicles to equip the vehicle with a snowplow for the purpose of removing snow from a ground surface. These vehicles include cars, jeeps, sport utility vehicles, pick-ups and the like. Each type of vehicle has a different frame structure and a different bumper design to accommodate the frame structure. At present, the most commonly used arrangement for attaching a snowplow blade to a vehicle involves pivotally connecting an A-frame which supports the blade to a frame extension below the front of the vehicle. Vertical displacement of the snowplow blade in the A-frame is provided by a lift-mount assembly. The lift-mount assembly serves primarily to raise, lower and support the plow blade, such as by raising the plow blade above the ground during transportation of the snowplow blade as well as during a snowplow operation. The lift-mount assembly typically includes a hydraulic cylinder, lift arm and chain or cable arrangement mounted above the vehicle frame. Typically, the A-frame is aligned with the vehicle frame below the front of the vehicle to provide proper blade alignment.
The A-frame generally includes a frame assembly supporting a plow blade forwardly of the vehicle and having an inner end design to be releasably hitched to the support structure beneath the vehicle. Detachment of the snowplow blade unit from the vehicle enables use of the vehicle for personal and/or work oriented purposes other than snowplowing.
Depending on the type of the frame mount used, the frame mount typically projects out beyond or coplanar with the bumper thereby defeating the purpose of the bumper. In addition, the frame mount becomes a potentially dangerous battering ramp when extended past the bumper, and is subject to being damaged itself in a collision. Such prior art lift assemblies are disclosed in U.S. Pat. Nos. 2,667,708; 3,214,138; 3,410,008; 3,456,369; and 3,987,562. In addition, these prior art mount assemblies include one or more of a number of structural disadvantages, such as a) excessive weight, b) exposure to adverse environmental conditions, c) potential physical damage during non-snowplowing use, d) high cost of manufacture, e) difficulty in mounting to a variety of vehicle frames, and f) undesirable aesthetics when used on a vehicle. More particularly, with regard to such disadvantages, these prior art lift mount assemblies are typically 1) mounted on the existing vehicle bumper or on a special cross member between the vehicle frame members which either replaces or is provided in addition to the bumper, or 2) are mounted on one of the vehicle's frame and bumper components and interconnected with the one another. Furthermore, due to the design of these prior art mounting systems, when the snow blade is elevated, the lift arm mounting members cause considerable stress at the point of connection between the mounting members and the vehicle as a result of the weight of the corresponding snowplow blade unit. Such forces necessitate structurally heavy mounting members and supports, and special structural interconnections there between in an effort to minimize damage and/or bending or breakage of the mounting members and/or support components. This results in undue weight to the support unit and increased complexity in the assembly and the repair of the support unit. The lift arm assemblies are also intended to remain on the vehicle when the snowplow unit is removed therefrom. This is undesirable from the stand point of the weight imposed on the front axle of the vehicle and can result in a violation of one or more governmental restrictions with respect to vehicle loading. In addition, one or more of the lift components project a considerable distance forward of the vehicle bumper thus exposing such components to damage or destruction should the vehicle impact against an object. Moreover, these components, when exposed to the elements year round, can begin to deteriorate, therefore requiring more frequent maintenance, repair and replacing, thus increasing the expense of using such an assembly. The permanent fixture of these components to the vehicle also can significantly deteriorate from the aesthetic appearance of the front of the vehicle during non-winter months.
Many efforts have been made to resolve several of these problems with respect to the use of snowplow blades. Assignees' U.S. Pat. No. 4,279,084 improves on a number of draw backs of prior art lift mount assemblies. This lift mount assembly reduces the number of modifications to the front end of the vehicle to accommodate the lift mount assembly. This lift mount assembly replaces projecting parts of the lift mount assembly with somewhat recessed exposed parts which do not bear the full impact of a collision should the vehicle impact against an object during non-snowplow use. However, the foremost part of the bracket portion of the lift mount assembly is located on the same vehicle plane as the foremost part of the bumper. Therefore, both the bumper and the lift mount bear the brunt of any collision. Potential damage to the lift mount assembly remains a likelihood on the collision. The lift mount assembly also must be positioned behind the bumper which can present installation problems. The mount assembly also requires some rigging to establish the top mounting point behind the bumper which can be troublesome for some vehicles.
Assignees' U.S. Pat. No. 5,036,608 improved on many of the remaining drawbacks of existing mount assemblies. The mount assembly is a two piece assembly wherein the housing unit is affixed to the frame of the vehicle beneath and behind the bumper of the vehicle thereby eliminating parts of the housing from being damaged on collision by the vehicle. The lift mount assembly also includes a support unit which releasably attaches to the housing and is designed to support components of the mount assembly to lift and lower the snowplow frame assembly. When the snowplow blade and A-frame are removed from the housing unit, the support unit may also be removed thereby eliminating projecting parts of the lift mount assembly from being exposed to damage. The removal of these components also enhances the authentic appearance of the vehicle during non-winter months and prevents the lift mount assembly components from being exposed to the elements throughout the year.
Although U.S. Pat. No. 5,036,608 is a significant improvement over prior art lift mount assemblies, the improved lift mount assembly does not address several problems with respect to the mounting of the lift assembly and blade mount assembly to various types of vehicles, the adjustment of the lift assembly to various types of vehicles, and the difficulty in attaching and detaching the lift assembly and/or snow blade mount assembly from the vehicle.